Masonry cavity walls have inner and outer vertical walls. The inner wall is typically constructed from wood with an inner surface of drywall, structural clay tile, vertical stacks of mortared bricks, or a shear concrete surface. The outer wall is generally constructed from courses of bricks that are held together by mortar. A space, or cavity, exists between the two walls.
The porous nature of brick allows water to enter the cavity. Also, moisture can condense on the inside of the wall under changing temperatures. Either way, water may collect in the cavity between the inner and outer wall.
The presence of moisture in the space between the inner wall and outer wall is undesirable for a number of reasons. First, the trapped moisture can degrade the inner and outer wall, causing a weakening of the structure. Second, the presence of water under freezing temperatures may also cause cracks in the walls when the water expands as it freezes. Trapped water in the cavity between the inner and outer walls may cause the walls to become discolored, and may even leak into the dwelling. Yet another undesirable outcome from the presence of trapped water is the formation of mold on the interior wall which can render the structure uninhabitable.
To overcome the problems associated with water trapped within a masonry cavity wall, weep holes are sometimes placed along the base of the outer wall. The weep holes allow water to pass from the cavity to drain outside the wall structure. During construction of a masonry cavity wall, excess mortar and other debris can and does fall between the inner and outer wall. When the bricks are laid during the erection of the outer wall, for example, mortar droppings are squeezed into the space between the walls. The excess mortar, as well as other debris, drops to the base of the cavity, and can block the weep holes.
There are other solutions which attempt to overcome these problems. For example, some builders place a small breathable structure in the weep hole, or alternatively a small shield in the weep hole, either of which attempts to prevent mortar and other debris from obstructing passage of air through the hole. However, even if successful in preventing obstruction of the weep hole, these small between-brick weep holes often do not have flow paths which are sufficiently large enough to aerate and dry out interior walls that are damp enough to support mold growth or other damage caused by excessive moisture.
The present invention presents novel and non-obvious methods and apparatus for venting a brick wall.